The invention relates to a laboratory reactor with a reaction vessel, closed and connected to a device for changing the pressure, i.e. with a device for creating overpressure or a vacuum, to accept media to be processed and/or to be mixed and/or to be made reacting with each other or at least with one processing and/or measuring aggregate or mixing and/or agitating device engaging said vessel, as well as a holder for receiving said vessel, which has a base facing a support area.
Such laboratory reactors are known in multiple forms and different designs. Frequently they are designed in a modular fashion and serve to optimize and reproduce chemical reaction, mixing, dispersing, and/or homogenization processes on a laboratory scale. For example, the following processes can be performed thereby:                the production of cremes, lotions, emulsions, and liposome-preparations of the pharmaceutical and cosmetic field,        the integration of solid matters, such as calcium carbonate, talcum, titanium dioxide, and other substances into liquid polymers,        the integration of additives and solid polymer compounds into mineral oils,        the grinding and defibration of solid matter and fibers in liquids and polymers.        
Such laboratory reactions can frequently be adjusted by the user to the respective objective. Here, for example temperature measuring devices, agitators, dispersing devices, and/or thermostats can be used, and also be adjusted in various manners, such as program-controlled via computers and/or microprocessors. Here, single-walled and dual-walled vessel can be used with or without bottom drains made from a special glass or stainless steel, with generally the basic equipment includes a stand system for connecting on the one hand the vessel and on the other hand the arrangements, apparatuses, and measuring devices to be used. The connection for the devices is frequently embodied such that the processing and measuring devices can be mounted above the vessel so that they can engage the vessel from above.
Additionally, laboratory reactors are known in which a drive shaft for a mixing device is inserted into the vessel through the bottom.
In such laboratory reactors for the processing of substances, frequently importance is given to very precisely (defined) amount, which during the processing may change, if applicable, and which are to be filled either successively or also simultaneously, or which may change during processing with regards to their weight or due to chemical reactions, if for example a heating function is included.
In order to allow filling or refilling or gradually adding additional material during processing it had to be ensured in the past that such substances are added in precisely the correct amount, i.e. each of them had to be measured in advance. This is considered cumbersome and expensive.